Inductance coil



INDUCTANGE COIL Filed Jan. 18, 1941 2 Sheets-Sheet 1 June 20, 1944.

T. M. FERRILL, JR

INDUGTANCE COIL Filed Jan.

2 Sheets-Sheet 2 firm/As MURRAY fie-2571.1. Jk.

Patented June 20, 1944 UNITED STATES PATENT OFFICE INDUCTANCE OOIL Thomas M. Ferrlll, Jr., Mineola, N. Y., assignor to National Company, Inc., Maiden, Mesa, a corporation of Massachusetts Application January 18, 1941, Serial No. 375,055

20 Claims.

The present invention relates to inductance coils, and more particularly to radio-frequency choke coils.

As is well known, it is not possible to produce a coil the impedance of which shall be solely inductive at all frequencies. No matter how carefully the materials of the coil are chosen, and no matter how scrupulously it is designed, the coil will have at least some capacitance, due to the fact that a condenser action takes place between adjacent convolutions. This well recognized capacitance is designated in the art as the distributed capacitance of the coil.

An object of the present invention is to provide a new and improved coil the distributed capacitance of which shall be greatly reduced.

Other and further objects will be explained hereinafter, and will be particularly pointed out in the appended claims.

The invention will now be explained more fully in connection with the accompanying drawings in which Fig. l is a side elevation of a coil embodying the invention in preferred form; Fig. 2 is a plan of the same; Fig. 3 is a section, upon an enlarged scale, taken substantially upon the line 3-3 of Fig. 2, looking in the direction of the arrows, a part being broken away; Figs. 4 and 5 are views similar to Fig. 1 of modifications; and Fig. 6 is a plot of the impedance, as a function of frequency, of a radio-frequency choke coil embodying the present invention.

According to a preferred embodiment of the invention, illustrated in Figs. 1, 2 and 3, the coil is constituted of a plurality of cylindrical singlelayer windings, occupying different axial positions, upon an insulating supporting structure 2, and with the diameters uf adjacent windings of abruptly different value, so that the adjacent windings are abruptly spaced radially. The diameter of the first layer winding 4, for example, is abruptly different from that of the next-adjacent, second layer winding 6, the diameter of the second layer winding 5 is abruptly different from that of the next-adjacent, third layer winding 8,

. and so 011. Further single-layer windings H], I2,

it and ii are shown in the preferred embodiment ever, is of little consequence, so long as no two adJacent windings have the same diameter.

The windings are continuously connected together, being made from a single wire, with the end or terminal convolution of each winding abruptly separated from the beginning convolution of the winding adjacently disposed thereto, the abrupt separation being spanned by the connecting wire extending between these terminal convolutions.

The right-hand-end convolution of the winding 4, for example, is connected continuously by a connecting wire I! to the left-hand-end convolution of the layer 8, and the right-hand-end convolution of the latter, continuously by a connecting wire 20 to the left-hand-end convolution of the winding 8. The connecting wire portions I8, 20, and so on, pass over flattened portions 22 disposed upon insulating rings 28 integrally formed upon the supporting structure 2.

By reason of the fact that the windings 4, 6, 8. HI, l2, l4 and it are constituted of single layers. there is less distributed capacitance than is the case with windings having a plurality of layers wound one about the other; for each of such plurality of layers would introduce a distributed capacitance by reason of its propinquity to another such layer. Even that less distributed capacitance of the single layer, furthermore, is reduced by abruptly separating each single-layer winding from its adjacent single-layer winding, as by having successively adjacent windings of abruptly different diameter.

Theoretically, the maximum desired effect would be produced by having the diameters or indicated in Fig. 6, has been found to have very satisfactory operation with a very high inductive impedance, as illustrated by the plot of the said Fig. 6, over a frequency range from 1.5 to 15 megacycles, and from 2'? megacvcles through and beyond 30 megacycles. With this very small unit, it is thus possible to include the amateur radio-frequency bands, in particular. 1.715 to 2.0, 3.5 to 4, 7 to 7.3, 14 to 14.4 and 28 to 30 megacycles, as indicated by the shaded areas of Hg. 6. This high inductive impedance is obtained by reason of the fact that, though the inductance oi the coil is high, its distributed capacitance is rather low.

One end of the inslating supporting structure I is shown supported upon a three-legged base 20 that supports also a small insulating pillar 30. One end of the coil is connected to a terminal 32 at the other end of the supporting structure 2, and the other end of the coil is connected to a terminal 34 supported by the pillar 3B.

The invention is obviously not restricted to use with cylindrical windings. Conical windings 36, for example, are illustrated in Fig. 4, where the connecting wires ll, 20, and so on, are shown extending from the base ll of one cone to the apex l0 0! the next-adjacent cone. It is not absolutely essential, indeed, that the windings, if cylindrical, be of different diameter. If sufilciently separated axially from one another, abruptly, as by means oi axial gaps Iii, as illustrated in Fig. 5, the windings 42 may be of the same diameter, with the connecting wires i8, 20, and so on, extending from the right-hand-end or end-terminal convolution of one winding to the left-hand-end or beginning-terminal convolution of the next-adjacent winding. In all cases, however, the coil comprises a plurality of single-layer windings that are abruptly separated from one another, and with the successive convolutions of each winding disposed at successively more distant positions axially of the windings.

The single-layer windings are shown with each convolution of each winding compactly disposed in contact with the convolutions adjacent thereto. If these convolutions were not compactly so disposed, of course, even less distributed capacitance would be introduced. The inductance, however, would likewise be reduced, because, owing to the increased length of the coil. the inductance per turn factor of the coil would be less. Separated windings o! the same diameter, as illustrated in Pig. 5, are less desirable from this point of view. Not only is the over-all length of the radio-frequency choke coil far greater than with the other illustrated arrangements, but the inductance per turn or convolution is also less. It is accordingly preferred. as illustrated in the remaining figures, to employ adjacently disposed windings the radial dimensions of which are abruptly different.

Further modifications will occur to persons skilled in the art, and all such are considered to fall within the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

1. An inductance coil comprising a plurality of single-layer continuously connected windings, the cross-dimensions oi adjacently disposed windings having abruptly diiferent values.

2. An inductance coil comprising a plurality of single-layer continuously connected windings occupying diil'erent. axial positions, adjacent portions oi adjacent windings having abruptly different cross-dimensions.

3. An inductance coil comprising a plurality of single-layer continuously connected cylindrical windings occupying different axial positions, the diameters of adjacent windings having abruptly diflerent values.

4. An inductance coil constituted of a plurality of abruptly separated single-layer windings occupying diiierent axial positions and continuously connected together by connecting wires, each convolution oi. each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions or each winding disposed at successively more distant positions axially oi the windings, and the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto.

5. All inductance coil constituted of a plurality of abruptly separated single-layer windings occupying diflerent axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of the windings, the wire connecting adjacent windings extendin from an endterminal convolution of one winding that is abruptly separated from a. beginning-terminal convolution of the winding disposed adjacent thereto, and the cross-dimensions of the adiacently disposed windings having abruptly different values.

6. An inductance coil constituted of a plurality of abruptly separated cylindrical single-layer windings occupying different axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of the windings, and the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto.

7. An inductance coil constituted of a plurality of abruptly separated cylindrical single-layer windings occupying different axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of the windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto, and the diameters of adjacently disposed windings having abruptly difierent values.

8. An inductance coil constituted of a plurality of abruptly separated cylindrical single-layer windings occupying difierent axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of the windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto, the diameters of adjacently disposed windings having abruptly difi'erent values, and alternately disposed windings having one diameter and the remaining windings another diameter.

9. An inductance coil constituted of a plurality of abruptly separated cylindrical single-layer windings occupying different axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of th windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto, the diameters of adjacently disposed windings having abruptly diflerent values, alternately disposed windings having one diameter and the remaining windings another diameter, and the windings being disposed adjacent to each other.

10. An inductance coil constituted oi a plurality of abruptly separated single-layer cylindrical windings occupying different axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially of the windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto, the diameters of adjacently disposed windings having abruptly different values, alternately disposed windings having one diameter and the remaining windings another diameter, and a terminal winding being oi smallest diameter and longer than the lengths of the other windings, the said other windings being of substantially equal length.

11. An inductance coil constituted of a plurality of abruptly separated single-layer conical windings occupying diilerent axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially oi the windings, and the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto.

12. An inductance coil constituted of a plurality of abruptly separated cylindrical single-layer windings occupying diilerent axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions 01' each winding disposed at successively more distant positions axially oi the windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginningterminal convolution of the winding disposed adjacent thereto, and the cylindrical windings being abruptly spaced axially.

13. An inductance coil comprising a plurality or single-layer continuously connected cylindrical windings abruptly spaced radially and occupying diiierent axial positions.

14. An inductance coil comprising a plurality of single-layer continuously connected windings abruptly spaced radially and occupying diilerent axial positions.

15. An inductance coil constituted of a plurality of abruptly separated single-layer windings occupying different axial positions and continuously connected together by connecting wires, each convolution of each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially or the windings, the wire connecting adjacent windings extending from an end-terminal convolution of one winding that is abruptly separated from a beginning-terminal convolution of the winding disposed adjacent thereto, the cross-dimensions of the adjacently disposed windin s having abruptly different values, and a terminal winding being of smallest cross-dimension and longer than the lengths of the other windings.

16. An inductance coil comprising a plurality of single-layer continuously connected windings, the cross-dimensions of adjacently disposed windings having abruptly different values, and alternately disposed windings having one cross-dimension and the remaining windings another crossdimension.

17. An inductance coil comprising a plurality oi single-layer continuously connected windings occupying diiferent axial positions, adjacent portions or adjacent windings having abruptly differentcross-dimensions, and alternately disposed windings having one cross-dimension and the remaining windings another cross-dimension.

18. An inductance coil comprising a plurality of single-layer continuously connected cylindrical windings occupying diflerent axial positions, the diameters of adjacent windings having abruptly diflerent values, and alternately disposed windings having one diameter and the remaining windings another diameter.

19. An inductance coil comprising a plurality of single-layer continuously connected cylindrical windings occupying diilerent axial positions, the diameters of adjacent windings having abruptly different values, alternately disposed windings having one diameter and the remaining windings another diameter. and a terminal winding being of smallest diameter and longer than the lengths of the other windings, the said other windings being of substantially equal length.

20. An inductance coil constituted of a plurality oi! abruptly separated single-layer windings of substantially the same cross-dimension occupying diiterent axial positions and continuously connected together by connecting wires, each convolution 0! each winding being compactly disposed in contact with the convolutions adjacent thereto but with successive convolutions of each winding disposed at successively more distant positions axially oi the windings, the wire connecting adiacent windings extending trmn an end-terminal convolution of one winding that is abruptly IE9- arated from a beginning-terminal convolution of the winding disposed adjacent thereto, and the cylindrical windings being smar ly spaced mouse u. manna. 

